Microwave-foamed epoxy resin-based porous composite material and preparation method thereof

Abstract

The invention belongs to the technical field of polymer functional composite materials, and particularly relates to a microwave foamed epoxy resin-based porous composite material and a preparation method thereof. The epoxy resin-based porous composite material is prepared from the following raw materials: an epoxy resin matrix, a foaming agent and a plurality of surface modified glass beads, and the epoxy resin matrix and the foaming agent are foamed and cured under the action of microwaves to form a three-dimensional interpenetrating porous structure with mutually communicated foam holes; the plurality of surface modified glass beads are uniformly dispersed in the three-dimensional interpenetrating porous structure. According to the invention, water is used as a green foaming agent, and efficient and uniform foaming of epoxy resin is realized by combining the heating characteristic of a microwave body; the surface modified glass beads are used as heterogeneous nucleation points, so that the cell size and distribution of the composite material are precisely regulated and controlled, and an ideal porous acoustic structure is formed; the interface strengthening effect mediated by the silane coupling agent remarkably improves the binding force of the filler and the matrix, and the mechanical property of the material is guaranteed while the lightweight of the material is realized.

Description

Technical Field

[0001] This invention belongs to the field of polymer functional composite materials technology, and particularly relates to a microwave-foamed epoxy resin-based porous composite material and its preparation method. Background Technology

[0002] Epoxy resin-based porous materials, especially foamed composites, show great promise for noise control in fields such as construction, transportation, and aerospace due to their lightweight, high specific strength, and designable multifunctionality. Traditional epoxy resin foaming technologies often rely on chemical foaming agents (such as azodicarbonamide) or physical foaming agents (such as supercritical CO2), which suffer from problems such as complex processes, high energy consumption, uneven cell size distribution, residual harmful substances, or stringent equipment requirements. Furthermore, to achieve wide-bandgap and high-efficiency sound absorption performance, functional fillers (such as hollow glass microspheres) are often introduced into the matrix to construct complex acoustic structures. However, the weak interfacial bonding between the filler and the resin matrix easily leads to stress concentration and performance degradation. Simultaneously, the dispersion and nucleation behavior of the filler during the foaming process is difficult to precisely control, limiting further improvements in the overall material performance.

[0003] Microwave heating technology, with its characteristics of volumetric heating, high efficiency, speed, and selective heating, provides a new approach for the processing of polymer materials. Water, as a clean, inexpensive, and high-dielectric-loss medium, can rapidly convert electromagnetic energy into heat energy in a microwave field, generating steam to act as a physical foaming agent, thus achieving a greener foaming process. However, how to utilize the synergistic effect of microwaves and water to precisely control the cell structure using water vapor as a template while simultaneously curing and crosslinking epoxy resin, and to achieve uniform dispersion and strong interfacial bonding of functional fillers, remains a technical bottleneck in the preparation of high-performance epoxy resin foamed composite materials. Existing composite material preparation processes typically involve filler modification, dispersion, foaming, and curing in separate steps, resulting in cumbersome processes and making it difficult to achieve integrated and precise control of microstructures (such as cell size, distribution, and filler interfaces).

[0004] Therefore, it is of great significance to develop an epoxy resin-based porous composite material that is simple to process, environmentally friendly, and can achieve integrated reinforcement of filler interface, precise control of cell structure, and rapid resin curing. Summary of the Invention

[0005] The main objective of this invention is to provide a microwave-foamed epoxy resin-based porous composite material and its preparation method, so as to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: According to a first aspect of the present invention, a microwave-foamed epoxy resin-based porous composite material is provided. The raw materials for preparing the epoxy resin-based porous composite material include an epoxy resin matrix, a foaming agent, and a plurality of surface-modified glass microspheres. The epoxy resin matrix and the foaming agent are foamed and cured under microwave action to form a three-dimensional interpenetrating porous structure with interconnected pores. The plurality of surface-modified glass microspheres are uniformly dispersed in the three-dimensional interpenetrating porous structure.

[0007] Furthermore, the raw materials for preparing the epoxy resin-based porous composite material include the following components by weight: 100 parts epoxy resin matrix, 3-20 parts surface-modified glass microspheres, 10-50 parts water, and 10-30 parts curing agent, wherein the surface-modified glass microspheres are hollow glass microspheres grafted with γ-aminopropyltriethoxysilane.

[0008] Furthermore, the epoxy resin is a bisphenol A type epoxy resin with an epoxy value of 0.48-0.54 eq / 100g; the curing agent is a cashew nut shell curing agent; and the water is deionized water.

[0009] Furthermore, the epoxy resin-based porous composite material has a porosity of 9%-38% and an average pore size of 0.15-0.70 mm; an average sound absorption coefficient of not less than 0.3 in the frequency range of 500-6000 Hz; a compressive strength of 0.3-1.8 MPa; and a compressive modulus of 2.0-14.0 MPa.

[0010] According to a first aspect of the present invention, a method for preparing a microwave-foamed epoxy resin-based porous composite material as described in any one of the present invention is provided, comprising the following steps: S1. Epoxy resin, surface-modified glass microspheres and water are mixed and subjected to mechanical stirring and ultrasonic treatment to obtain a uniform premix. S2. Add a curing agent to the premix obtained in step S1, stir and mix to obtain a foamable mixture; S3. Inject the foamable mixture obtained in step S2 into a mold, and then place the mold in a microwave reactor for microwave radiation to achieve simultaneous foaming and curing, thereby obtaining a foamed body. S4. After cooling the foam from step S3 to room temperature, demold it to obtain the epoxy resin-based porous composite material.

[0011] Furthermore, before step S1, a surface modification treatment of the glass microspheres is included: after the glass microspheres are subjected to alkaline hydroxylation treatment, they are then grafted with the silane coupling agent APTES to obtain surface-modified glass microspheres.

[0012] Furthermore, in step S1, the mechanical stirring speed is 800-1500 rpm, and the time is 5-30 minutes; the ultrasonic treatment power is 200-500W, and the time is 3-10 minutes; and / or, The microwave radiation described in S3 has a frequency of 2.45 GHz, a power of 150-250 W, and a duration of 4-6 minutes.

[0013] Furthermore, in step S3, the mold is made of silicone rubber, polytetrafluoroethylene, or a metal mold coated with a release agent, and the peak internal temperature during the microwave radiation process is controlled within the range of 100-140℃.

[0014] Furthermore, in step S1, the raw materials for preparing the epoxy resin-based porous composite material contain 20wt% water, 5wt% glass microspheres, 200W microwave radiation power, and 5 minutes of radiation time; the epoxy resin-based porous composite material has a porosity of 9.85%, an average pore size of 0.145mm, and a compressive strength of 1.84MPa.

[0015] According to a third aspect of the present invention, the use of an epoxy resin-based porous composite material foamed by any one of the present inventions in the preparation of broadband sound-absorbing and / or lightweight structural components is provided.

[0016] Compared with the prior art, the advantages of the present invention include: This invention provides a microwave-foamed epoxy resin-based porous composite material and its preparation method. (1) This invention achieves efficient and uniform foaming of epoxy resin by using water as a green foaming agent and combining it with the heating characteristics of microwave body; by using surface-modified glass microspheres as heterogeneous nucleation points, the size and distribution of the pores of the composite material are precisely controlled, forming an ideal porous acoustic structure; the interface strengthening effect mediated by silane coupling agent significantly improves the bonding force between the filler and the matrix, thereby ensuring the necessary mechanical support performance while achieving material lightweighting.

[0017] (2) The microwave hydrodynamic foaming process adopted in this invention integrates the mixing, foaming and curing processes in a microwave field and completes them in one step. The process is simple and efficient. Water replaces the traditional chemical foaming agent, which fundamentally eliminates the residue of volatile organic compounds. The process is green and environmentally friendly. Microwave heating is fast and uniform, which greatly shortens the production cycle, reduces energy consumption, and has good potential for large-scale production.

[0018] (3) The epoxy resin-based porous composite material prepared by this invention has a synergistic effect between its porous structure and the reinforcing interface, giving it both excellent broadband sound absorption performance and good mechanical properties. This material shows broad application prospects in building sound insulation, NVH optimization of transportation vehicles, and noise reduction of industrial equipment, providing an effective technical solution for solving the demand for sound-absorbing materials that combine lightweight and high performance. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A scanning electron microscope image of the modified glass microspheres prepared in Example 1; Figure 2 Scanning electron microscope image of unmodified glass microspheres; Figure 3 This is a photograph of the epoxy resin foam material prepared in Example 1; Figure 4 The mechanical properties of the microwave-foamed epoxy resin foam material prepared in Example 1 are shown in the figure. Detailed Implementation

[0020] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0021] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0022] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials used in the following embodiments are commercially available.

[0023] This invention provides a microwave-foamed epoxy resin-based porous composite material and its preparation method. Epoxy resin, surface-modified glass microspheres (A-HGM), a curing agent, and water are mixed and then microwave-treated to form a composite material with a uniform three-dimensional porous structure. This preparation method is simple, efficient, and rapid, using water as a green foaming agent, achieving environmentally friendly preparation of porous materials. The resulting material possesses both good sound absorption and mechanical properties, making it suitable for lightweight sound absorption and structural components.

[0024] Specifically, the following steps are included: 1. Epoxy resin, surface-modified glass microspheres and water are mixed in the following proportions by weight: 100 parts epoxy resin, 3-20 parts surface-modified glass microspheres and 10-50 parts water. The mixture is mechanically stirred in a mixer at 500-1500 rpm for 5-30 minutes and then subjected to ultrasonic treatment to obtain a premix. 2. Add 10-30 parts of curing agent to the premix and continue stirring for 5-15 minutes to obtain a foamable mixture; 3. Inject the foamable mixture into a mold, place it in a microwave reactor, and allow it to foam and cure under microwave radiation for 2-8 minutes at a frequency of 2.45 GHz and a power of 100-300W to obtain a foamed body; 4. After the foam has cooled naturally to room temperature, it is demolded to obtain the epoxy resin-based porous composite material.

[0025] This invention uses epoxy resin as a continuous matrix, surface-modified glass microspheres as functional fillers, and water foaming to form a three-dimensional interpenetrating network structure, thus constructing a lightweight functional material integrating "epoxy resin matrix - interface reinforcement phase - porous structure".

[0026] Preferably, the components are as follows by mass: 100 parts epoxy resin, 3-20 parts surface-modified glass microspheres, 10-50 parts water as a foaming agent, and 10-30 parts curing agent.

[0027] Preferably, the surface-modified glass microspheres are hollow glass microspheres that have undergone surface grafting treatment with γ-aminopropyltriethoxysilane (APTES).

[0028] Preferably, the composite material has a controllable porous structure with a porosity of 9%-38% and an average pore size of 0.15-0.70 mm.

[0029] This invention also provides a method for preparing the above-mentioned microwave-foamed epoxy resin-based porous composite material, comprising the following steps: S1. Material premixing and dispersion: Epoxy resin, surface-modified glass microspheres and water are mixed in proportion, and then mechanically stirred and ultrasonically treated to obtain a uniformly dispersed premix. S2, Curing System Introduction: Add curing agent to the premix of S1, continue stirring and mixing until homogeneous, to obtain a homogeneous and stable foamable mixture; S3, Microwave Integrated Foaming and Curing: The foamable mixture of S2 is injected into a mold and placed in a microwave reactor. Microwave radiation is applied at a set power and time to achieve simultaneous foaming and cross-linking curing of the material, resulting in a shaped foam. S4. Post-molding treatment: After cooling the foam from S3 to room temperature, demold it to obtain the porous composite material.

[0030] Preferably, the mixing and dispersing process in S1 and S2 includes: first, mechanical stirring at a speed of 800-1500 rpm for 5-30 minutes, and then ultrasonic treatment at a power of 200-500 W for 3-10 minutes.

[0031] Preferably, the curing agent in S2 is a cashew nut phenol curing agent.

[0032] Preferably, the microwave radiation in S3 has a frequency of 2.45 GHz, a power of 150-250 W, and a duration of 4-6 minutes.

[0033] Preferably, the mold in S3 is made of silicone rubber, polytetrafluoroethylene, or a metal mold coated with a release agent.

[0034] This invention also provides an application of the microwave-foamed epoxy resin-based porous composite material prepared by the above method in broadband sound-absorbing components. The material has an average sound absorption coefficient of not less than 0.3 in the frequency range of 500-6000 Hz and a compressive strength of 0.3-1.8 MPa, making it suitable for applications such as building sound insulation, vehicle interior decoration, and noise reduction in industrial equipment.

[0035] The design concept of this invention is as follows: Deionized water is used as the foaming agent, which is widely available, green, and non-toxic. In a microwave field, due to dielectric loss, it can rapidly convert electromagnetic energy into heat energy, generating steam pressure to drive foaming. Ordinary glass microspheres have poor interfacial compatibility with epoxy resin matrices, easily agglomerating during foaming and leading to coarsening of the pores and a decrease in mechanical properties. This invention modifies the surface of glass microspheres by grafting with a silane coupling agent (APTES), introducing amino functional groups that can chemically react with epoxy resin onto their surface. This modification process significantly strengthens the interfacial bonding between the inorganic filler and the organic matrix, effectively improving the mechanical properties of the composite material (such as compressive strength and modulus). More importantly, it allows the modified glass microspheres to be uniformly dispersed and act as efficient heterogeneous nucleation sites during foaming, precisely guiding and controlling the nucleation, growth, and distribution of water vapor bubbles, thereby obtaining an ideal porous structure with uniform pore size and controllable structure. The rapid and uniform heating characteristics provided by microwave heating ensure a good match and synergy between the resin curing reaction kinetics and the expansion kinetics of the foaming process, ultimately realizing the integrated design and preparation of composite materials that are lightweight, structurally uniform, and functionally (sound absorption) highly efficient.

[0036] The advantages of this invention are as follows: Using water as a green foaming agent and combining it with integrated rapid heating via a microwave field, this invention achieves highly efficient foaming and simultaneous curing of epoxy resin. By introducing surface-modified glass microspheres as heterogeneous nucleation sites and reinforcing phases, the pore structure and interfacial bonding of the composite material are precisely controlled. Compared with traditional processes, this invention shortens the curing and foaming time from 120 minutes to 4-6 minutes, increasing efficiency by more than 20 times, and fundamentally avoids the use of chemical foaming agents, achieving zero addition of volatile organic compounds. The prepared material possesses both excellent broadband sound absorption performance and good mechanical strength. The material has an average sound absorption coefficient of 0.48 across the entire frequency range of 500-6000 Hz and a compression modulus of 13.8 MPa. Furthermore, the porosity, pore size, and mechanical properties can be linearly controlled over a wide range through composition and process parameters to meet diverse application requirements. This method is simple, green, and efficient, making it suitable for large-scale production.

[0037] To better understand the technical solution of the present invention, the following detailed discussion is provided in conjunction with specific embodiments.

[0038] Example 1 1. Preparation of surface-modified glass microspheres (A-HGM): 10g of hollow glass microspheres were placed in 0.3 mol / L NaOH solution and stirred at 60℃ for 4 hours. After washing and drying, hydroxylated glass microspheres were obtained. These microspheres were then added to a hydrolysate prepared from 1g APTES and 200mL of ethanol-water (volume ratio 9:1) solution and reacted at 60℃ for 4 hours. After washing and drying, A-HGM was obtained.

[0039] 2. Weigh 100g of epoxy resin (E51), 20g of deionized water, and 5g of A-HGM, place them in a beaker, first mechanically stir at 1200 rpm for 5 minutes, then sonicate at 300 W for 5 minutes to obtain the premix.

[0040] 3. Add 20g of cashew phenol curing agent to the premix and continue stirring at 1200 rpm for 10 minutes to obtain a foamable mixture.

[0041] 4. Pour the mixture into a cylindrical silicone mold (30 mm in diameter), place it in a microwave reactor, set the microwave power to 200 W, and the radiation time to 5 minutes.

[0042] 5. After the reaction is complete, remove the mold and allow it to cool naturally to room temperature. Demold the mold to obtain the composite material sample, which is denoted as sample D1.

[0043] From the appendix Figure 1 and Figure 2 The scanning electron microscope (SEM) comparison images show that, compared with the unmodified glass microspheres (HGM), the surface of the surface-modified glass microspheres (A-HGM) prepared in Example 1 changed from smooth to significantly rough, exhibiting uniform granular attachments. This confirms the successful grafting of the silane coupling agent APTES and the formation of the surface-modified layer.

[0044] From the appendix Figure 3 As can be seen from the physical images, the epoxy resin-based porous composite material sample (D1) prepared in Example 1 has a regular cylindrical shape, and a uniformly distributed pore structure can be observed on its surface and cross-section, which macroscopically proves that the microwave foaming process forms a good three-dimensional porous whole.

[0045] From the appendix Figure 4 As can be seen from the compressive stress-strain curve, the sample (D1) of Example 1 exhibits typical elastoplastic behavior during compression. Its curve can be used to calculate key mechanical parameters such as the compressive strength and compressive modulus of the material, intuitively demonstrating the structural support potential of the material.

[0046] Example 2 1. Prepare A-HGM according to the method in Example 1.

[0047] 2. Weigh 100g of epoxy resin, 20g of deionized water, and 9g of A-HGM, and mix and disperse them according to the method in Example 1.

[0048] 3. Add 20g of cashew nut hardener and mix well.

[0049] 4. Inject into the mold and irradiate with microwave power of 200 W for 5 minutes to allow it to foam and cure.

[0050] 5. Cool and demold to obtain sample D2.

[0051] Summary: Compared with Example 1, Example 2 increased the content of A-HGM. Scanning electron microscopy (SEM) observation showed that the average pore size of sample D2 (approximately 0.312 mm) was larger than that of D1 (approximately 0.145 mm), and the porosity was also increased. According to ASTM E1050 standard testing, the average sound absorption coefficient of sample D5 in the frequency range of 500-6000 Hz was 0.48. According to ASTM D695 standard testing, its compression modulus reached 13.8 MPa, exhibiting both high mechanical modulus and good broadband sound absorption performance.

[0052] Example 3 1. Without grafting APTES onto the glass microspheres, hydroxylation treatment was performed only according to the method in Example 1 to obtain hydroxylated glass microspheres (HGM).

[0053] 2. Weigh 100g of epoxy resin, 20g of deionized water, and 9g of HGM, and mix and disperse them according to the method in Example 1.

[0054] 3. Add 20g of cashew nut hardener and mix well.

[0055] 4. Inject into the mold and irradiate with microwave power of 200 W for 5 minutes to allow it to foam and cure.

[0056] 5. Cool and demold to obtain sample D3.

[0057] Summary: Compared to Example 2, Example 3 used ungrafted glass microspheres. SEM observation showed that the D3 sample had a larger pore size (approximately 0.702 mm) and poorer uniformity of distribution. Mechanical property testing according to ASTM D695 standard showed that the compressive strength of D3 was significantly lower than that of D2. This indicates that APTES grafting treatment enhanced interfacial bonding, optimized pore structure, and improved mechanical properties.

[0058] Example 4 1. Prepare A-HGM according to the method in Example 1.

[0059] 2. Weigh 100g of epoxy resin, 40g of deionized water, and 5g of A-HGM, and mix and disperse them according to the method in Example 1.

[0060] 3. Add 20g of cashew nut hardener and mix well.

[0061] 4. Inject into the mold and irradiate with microwave power of 200 W for 5 minutes to allow it to foam and cure.

[0062] 5. Cool and demold to obtain sample D4.

[0063] Summary: Compared with Example 1, Example 4 increased the water content. The porosity of the resulting sample D4 was significantly improved, and the average pore size was also increased. Sound absorption tests conducted according to ASTM E1050 standard showed that the sound absorption performance of D4 was significantly improved in the low-frequency range (500-1000 Hz), indicating that the sound absorption frequency range of the material can be controlled by adjusting the water content.

[0064] Comparative Example 1 1. Prepare A-HGM and premix (containing epoxy resin and A-HGM) according to the method in Example 1.

[0065] 2. Add 20g of cashew phenol curing agent to the premix and mix well.

[0066] 3. Pour the mixture into a mold, place it in a microwave reactor, and irradiate it for 5 minutes at a power of 200 W.

[0067] 4. Cool and demold to obtain sample CD1.

[0068] 5. Summary: Compared with Example 1, no water was added in Comparative Example 1. The resulting sample CD1 did not form a porous structure and was a solid material, and the degree of curing reaction may have been affected. This indicates that water is an indispensable foaming agent in this invention and is a prerequisite for the formation of a porous structure.

[0069] Comparative Example 2 1. Prepare A-HGM and a foamable mixture (containing epoxy resin, A-HGM, water, and curing agent) according to the method of Example 1.

[0070] 2. Pour the mixture into the mold and place it in a 60°C oven to cure for 120 minutes.

[0071] 3. Cool and demold to obtain sample CD2.

[0072] Summary: In Comparative Example 2, compared to Example 1, conventional oven heating was used instead of microwave radiation. While the resulting sample CD2 could foam, the required curing time was extremely long (120 minutes vs. 5 minutes), and the cell size was uneven and relatively large. This indicates that microwave heating can significantly improve curing efficiency and helps to form more uniform and finer cells.

[0073] Table 1

[0074] As shown in the table above, the method of this invention (Examples 1, 2, and 4) can prepare porous materials with controllable pore size and porosity in a very short time (5 minutes). The comparative examples demonstrate that water as a foaming agent and microwave heating play a decisive role in achieving efficient foaming, shortening process time, and obtaining an ideal cell structure. Meanwhile, surface modification of the glass microspheres (comparing D2 and D3) is crucial for obtaining smaller, more uniform pores and superior mechanical properties.

[0075] The above descriptions are merely some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A microwave-foamed epoxy resin-based porous composite material, characterized in that: The raw materials for preparing the epoxy resin-based porous composite material include an epoxy resin matrix, a foaming agent, and a plurality of surface-modified glass microspheres. The epoxy resin matrix and the foaming agent are foamed and cured under microwave irradiation to form a three-dimensional interpenetrating porous structure with interconnected pores. The plurality of surface-modified glass microspheres are uniformly dispersed in the three-dimensional interpenetrating porous structure.

2. The microwave-foamed epoxy resin-based porous composite material according to claim 1, characterized in that, The raw materials for preparing the epoxy resin-based porous composite material include the following components by weight: 100 parts epoxy resin matrix, 3-20 parts surface-modified glass microspheres, 10-50 parts water, and 10-30 parts curing agent. The surface-modified glass microspheres are hollow glass microspheres grafted with γ-aminopropyltriethoxysilane.

3. The microwave-foamed epoxy resin-based porous composite material according to claim 2, characterized in that, The epoxy resin is a bisphenol A type epoxy resin with an epoxy value of 0.48-0.54 eq / 100g; the curing agent is cashew nut shell curing agent; and the water is deionized water.

4. The microwave-foamed epoxy resin-based porous composite material according to claim 1 or 2, characterized in that: The epoxy resin-based porous composite material has a porosity of 9%-38% and an average pore size of 0.15-0.70 mm; an average sound absorption coefficient of not less than 0.3 in the frequency range of 500-6000 Hz; a compressive strength of 0.3-1.8 MPa; and a compressive modulus of 2.0-14.0 MPa.

5. A method for preparing a microwave-foamed epoxy resin-based porous composite material as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Epoxy resin, surface-modified glass microspheres and water are mixed and subjected to mechanical stirring and ultrasonic treatment to obtain a uniform premix. S2. Add a curing agent to the premix obtained in step S1, stir and mix to obtain a foamable mixture; S3. Inject the foamable mixture obtained in step S2 into a mold, and then place the mold in a microwave reactor for microwave radiation to achieve simultaneous foaming and curing, thereby obtaining a foamed body. S4. After cooling the foam from step S3 to room temperature, demold it to obtain the epoxy resin-based porous composite material.

6. The preparation method according to claim 5, characterized in that, Before step S1, the process also includes a surface modification treatment of the glass microspheres: after the glass microspheres are subjected to alkaline hydroxylation treatment, they are then grafted with the silane coupling agent APTES to obtain surface-modified glass microspheres.

7. The preparation method according to claim 5, characterized in that, The mechanical stirring in step S1 is performed at a speed of 800-1500 rpm for 5-30 minutes; the ultrasonic treatment is performed at a power of 200-500 W for 3-10 minutes; and / or, The microwave radiation described in S3 has a frequency of 2.45 GHz, a power of 150-250 W, and a duration of 4-6 minutes.

8. The preparation method according to claim 5, characterized in that: In step S3, the mold is made of silicone rubber, polytetrafluoroethylene, or a metal mold coated with a release agent, and the peak internal temperature during the microwave radiation process is controlled within the range of 100-140℃.

9. The preparation method according to claim 5, characterized in that: In step S1, the raw materials for preparing the epoxy resin-based porous composite material contain 20 wt% water, 5 wt% glass microspheres, 200 W microwave radiation power, and 5 minutes of radiation time; the epoxy resin-based porous composite material has a porosity of 9.85%, an average pore size of 0.145 mm, and a compressive strength of 1.84 MPa.

10. The use of a microwave-foamed epoxy resin-based porous composite material as described in any one of claims 1-4 in the preparation of broadband sound-absorbing and / or lightweight structural components.

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